Exchange spring driven spin flop transition in ErFe2∕YFe2 multilayers

Abstract

Abstract.Magnetization loops for (110) MBE grown ErFe 2 /YFe 2 multilayer films are presented and discussed. The magnetocrystalline easy axis for the Er layers is parallel to a <111> type crystal axis, with the out of plane <111> axes favoured by the strain. For fields applied along the (110) crystal growth axis, out-of-plane magnetic exchange springs are set up in the magnetically soft YFe 2 layers. For multilayer films that display exchange spring dominated reversal at low temperatures, there is a cross-over temperature above which there are additional transitions at high fields. These features are interpreted using micro-magnetic modelling. At sufficiently high fields, applied perpendicular to the multilayer film plane, the energy is minimized by an exchange spring driven multilayer spin flop. In this state, the average magnetization of the ErFe 2 layers switches into a nominally hard in-plane <111> axis, perpendicular to the applied field.

Magnetic switching modes for exchange spring systems with competing anisotropies

“…modes of a configurable system with a variable YFe 2 layer thickness. We find the generalized switching modes observed for particular DyFe 2 /YFe 2 [24,25] and ErFe 2 /YFe 2 [26] multilayers: a mode of independent switching of the RE compounds into the applied field direction with exchange spring winding of the YFe 2 compound at LT, a switching mode where the ErFe 2 moments reverse via an intermediate spin flop state at MT, and an YFe 2 dominated switching mode with an unwinding of the RE compounds against the applied field direction at HT.…”

“…The magnetization characteristics of specific DyFe 2 /YFe 2 and ErFe 2 /YFe 2 systems are described elsewhere [24][25][26]. We will now focus on generalized [10 nm ErFe 2 /nYFe 2 /4 nm DyFe 2 /nYFe 2 ] systems with different n, and start with n ¼ 20 nm.…”

Engineering magnetic nanostructures with inverse hysteresis loops

“…Negative coercivity in magnetic superlattices and exchange coupled multilayers is attributed to strong antiferromagnetic interlayer coupling [10][11][12][15][16][17]. A complex spin structure was observed in exchange spring magnets with a spin flop transition [14,18]. In addition to these heterostructures based on antiferromagnetic interactions, inverse hysteresis loops can arise from a different microscopic origin.…”

“…One unusual finding was the appearance of inverse hysteresis loops in magnetic superlattices [10][11][12] and hard and soft coupled multilayers [13,14].…”

Exchange-spring driven spin-flop transition in DyFe 2 /YFe 2 superlattices

“…This finding highlights the importance of knowing the detailed magnetic interactions in the interpretation of magnetometry data. In passing, we would like to note that a similar spin-flop transition has been observed in antiferromagnetically-coupled ErFe 2 /YFe 2 superlattices by traditional magnetometry [11] and XMCD measurements [12].…”